The present disclosure generally relates to eye tracking, and specifically to eye tracking using a time multiplexed illumination source.
Eye tracking is an important feature for head-mounted display (HMD) systems including systems used in virtual reality (VR) applications. By tracking an orientation of a user's eye, the HMD display system may be able to adjust the content being displayed to the user in order to improve clarity and immersion. The HMD may also allow the user to interact with virtual content based upon the user's eye orientation (e.g., the user may select a displayed virtual object by staring at the object).
In some cases, eye tracking may be performed by projecting a light pattern comprising a plurality of light beams towards the eye of the user, and detecting the locations of reflections, referred to as glints, on the user's eye resulting from the projected light pattern. However, some of the reflected glints may be obscured by the user's pupil, eyelids, or eyelashes. In some cases, different glints may be detected more accurately or identified with better signal-to-noise ratio (SNR), based upon the orientation of the user's eye and/or variations in geometry between the eyes of different users. In addition, the number and intensity of the light beams that can be projected at a time towards the user's eye may be limited due to safety reasons, potentially reducing the number and intensity of the reflected glints.